A US company, called Grail, said it sent a form letter to some customers who had bought its Galleri test, which detects a marker for more than 50 types of cancer, stating incorrectly that a cancer signal was detected.

The company blamed a vendor, PWN Health, for the error, citing a "software configuration issue."

In a statement, PWN Health said it said the problem was due to "a misconfiguration of our patient engagement platform used to send templated communications to individuals."

It added that it had added processes to ensure such a mistake doesn't occur again and started contacting the people who received the erroneous letters within 36 hours. The error comes amid increased demand for healthcare screening tests, especially for chronic diseases like cancer.

Grail is billing its service as a complement to routine single-cancer tests for diseases such as colon or breast cancer and said that the blood test can detect forms of the disease that aren't routinely screened for, such as in the gallbladder and pancreas.

Grail said it hadn’t received reports of patient harm or "adverse events" due to the erroneous letters.

The spokeswoman added that more than half the erroneous letters were sent to customers who hadn't had their blood drawn yet for the Galleri test.